EFFECT OF EFFLUENT IN CONTINUOUS TYPE ANAEROBIC DIGESTION

Abstract

The anaerobic digestion (AD) of biomass feed materials like Prosopis juliflora pods (PJP), dry leaves (DL), water hyacinth (WH), and cow manure was investigated in a batch and continuous type of digestion. The daily biogas yield and the composition of biogas and the cumulative biogas yield were evaluated for each experiment. The batch experiment was conducted to find the hydraulic retention time of the feed materials. The continuous digestion was conducted under three different phases. The first phase was batch digestion for startup the experiment, the second phase was to continuously feed the materials without microorganism and the third phase was continuously fed the materials with the effluent filtrate. For an HRT of 50 days, the average biogas production of 13.2 l/day was shown by the batch experiment. The average biogas production of 19.7 l/ day was shown by the continuous type of digestion third phase in 40 days. Moreover, it showed the highest biogas composition (CH4:75.73% and CO2:24.08%). However, the second phase performed worst in the average biogas production (9.4 l/day) in 20 days and the biogas composition (CH4:69.58% and CO2:29.06%). After stabilization (from the 15th day) of the third phase, experiment feed materials with effluent filtrate gave the maximum average biogas yield (23.2 l/day). Overall these studies show that the addition of effluent filtrate with the feed material can be a promising technique for improving biogas production.